In the past, scientists believed that the production of oxygen depended on photosynthesis. However, researchers now suggest that oxygen can also be produced in areas deep in the ocean where sunlight does not reach. In regions of the Pacific Ocean seabed where sunlight cannot penetrate, researchers have discovered the generation of “dark oxygen,” which may challenge traditional understanding of how oxygen is produced on Earth.
This new finding challenges the theory that oxygen is only generated through photosynthesis, which requires sunlight. It raises new questions about the origin of life. “We may need to rethink the question of where aerobic life may have initially appeared,” said Professor Andrew Sweetman of the Scottish Marine Science Association in a press release.
Sweetman’s research team published their findings in the journal Nature Geoscience on July 22.
Scientists are still not clear on how oxygen is produced in the pitch-black depths of the ocean, but they speculate that it may be related to charged mineral substances known as “polymetallic nodules,” varying in size from tiny particles to the size of potatoes.
These nodules, described by Sweetman as “batteries in rocks,” may use their charge to electrolyze seawater, splitting it into hydrogen and oxygen.
“The traditional view is that oxygen was first produced about three billion years ago by ancient microbes known as cyanobacteria, and life gradually evolved to become more complex,” said Nicholas Owens, Director of the Scottish Marine Science Association. “This potential alternative source of oxygen prompts us to thoroughly reexamine this issue.”
Researchers conducted tests on the seabed and collected samples for testing on the ground, with consistent results showing an increase in oxygen levels near the “polymetallic nodules.”
Seawater can be electrolyzed into hydrogen and oxygen with 1.5 volts of power, equivalent to a AA battery. Researchers found that some nodules had voltages as high as 0.95 volts, and when multiple nodules were combined, higher voltages could be produced.
Polymetallic nodules contain metals such as manganese, nickel, and cobalt, which can be used to manufacture lithium-ion batteries found in consumer electronics, household appliances, and electric vehicles.
Chemistry professor Franz Geiger of Northwestern University, who participated in the study, mentioned in another press release that the Clarion-Clipperton Zone in the Pacific Ocean may hold enough polymetallic nodules to meet global energy needs for decades.
However, he also emphasized the need for cautious mining operations to avoid depleting the oxygen needed by marine life in the area.
Geiger stated in an interview with NPR, “We must be very cautious to ensure that mining operations do not harm deep-sea organisms in terms of levels and frequency.”
He noted that some companies conducted exploration missions for deep-sea mining in the 1970s and 80s, and recent studies indicate that these activities may have had long-term impacts on local marine life.
Geiger explained, “A few years ago, a group of marine biologists returned to areas mined 40 years ago and found hardly any life present. In contrast, just a few hundred meters away in untouched areas, life remained diverse and vibrant.”